At this point, most of us are pretty canny about shady food additives in our food (ahem, high-fructose corn syrup, much?). But there are still some sneaky ingredients that we as consumers often are still in the dark about, like phosphates.

Did you hear crickets when reading that word? Don’t blame you. It’s a very common food additive, present in lots of packaged foods, but it’s been flying under the radar for years. Yet a growing number of studies link it to some pretty undesirable side effects, from heart disease to early death (gulp).

It’s also hard to accurately determine just how much phosphorus you’re consuming. “It’s not a required nutrient listed on food and drink labels, so a lot of companies are not analyzing amounts of phosphates in food,” says Christy Brissette, R.D., President of 80 Twenty Nutrition. “It’s possible that we’re getting too much of it.”

Before you start to panic, though, here’s what food experts want you to know about phosphates.

What are phosphates, exactly?

Backing up for a second: Phosphorus is a mineral that’s naturally found in protein-rich foods including dairy, fish, meat, and eggs—and your body needs it to help your kidneys, bones, and muscles function properly. “It’s part of pretty much every cell in our body,” says nutritionist Jessica Cording, R.D. Because phosphorus works with calcium to support strong bones, you’ll often see it added to calcium supplements.

Phosphate, on the other hand, is an inorganic (read: not naturally derived) derivative of phosphorus that’s often added to processed foods. “Usually it’s not for nutritional benefits but for food science,” says Brissette. Phosphates are commonly used in processed cheese as emulsifiers to keep oil and water mixed together. In sodas, iced teas, and French fries, phosphates add color; they’re also found in powdered milk, powdered coffee, and pudding. The most common—and surprising—place you’ll find phosphates, however, is in meat, poultry, and seafood. “It’s injected in a water solution to help the meat retain more water when you recook it,” says Brissette.

What’s the difference between naturally-occurring phosphorus and the food additive?

While our bodies absorb about 50 to 60 percent of naturally-occurring phosphorus in the foods we eat, as a food additive the rate jumps to 90 percent. “In general, nutrients are bound with other compounds in food,” explains Brissette. “In addition to the calcium you’re getting from leafy greens, for example, there are natural ‘anti-nutrients’ in the food that make it more challenging to absorb.” Phosphate additives, however, are much more easily absorbed by the body, likely because they aren’t “bound” to any other chemicals in the same way that the phosphorus in food is. This means you’re getting a ton more of the compound in a serving than you normally would if you just ate a whole food that naturally contains phosphorus.

Are there any actual risks of eating too many phosphates?

The FDA classifies various types of phosphates as “generally recognized as safe,” notes Cording. But the Environmental Working Group lists sodium phosphate (a common type used in over 6,000 food products) as a “moderate concern” in foods, and there has been quite a bit of research linking it to potential health risks. Higher phosphate intake has been associated with increased risk of death for people with kidney disease. “The kidneys, especially if they’re already weakened from chronic kidney disease, can have a really hard time filtering it out of your blood effectively,” says Cording.

Some studies have also noted an increased risk of cardiovascular disease for people with elevated levels of phosphorus in their blood. “Researchers think the reason is that phosphorus helps us absorb calcium. By having high levels of phosphorus in your blood, you can develop calcium deposits and hardening of the arteries in the heart,” explains Brissette. Additional studies in animals have tied high levels of phosphate intake to an increased risk of high blood pressure and even a sedentary lifestyle.

However, most of this research is focused on association, not causation. There’s a chance that people with the highest phosphate intake just eat more highly-processed foods in general, since that’s where phosphates are commonly found—and those foods have other ingredients (sodium, refined carbs) that negatively impact heart health. Studies do adjust their findings to consider factors like diet and exercise, but “that’s an artificial way to manipulate numbers,” Brissette says. Without a randomized controlled trial of phosphate intake—where some people are randomly put on a high-phosphorus diet and others aren’t, and the outcomes in the two groups are compared over time—it’s hard to say with any certainty that phosphates are truly causing these effects, says Brissette.

Still, the research is convincing enough that it warrants a second look at your diet. “If you already have heart or kidney issues, be careful about eating foods with phosphate added,” says Cording.

How much phosphorus should I aim to eat?

Brissette says the recommended daily amount of phosphorus for most healthy adults is 700 mg. You’d hit that recommendation in just a couple of servings of seafood (300 to 400 mg), meat (200 to 300 mg in 150 grams of pork or beef), or dairy (100 to 200 mg) that hasn’t been processed with phosphates. In fact, most of us are getting well more than we need: A 2018 European study found adults are on average eating about twice that, which the authors attribute to all of us eating more processed foods containing phosphate additives. The Institutes of Medicine says the safe upper limit is 4,000 mg per day in healthy adults (barring kidney issues).

How can you avoid phosphates?

While you won’t often see phosphorus counted as a nutrient like sodium or saturated fat on packaged food labels, it does appear on the ingredients list under a lot of different names. Brissette says to try and avoid products with any ingredient that includes the letters “phos.”

It gets a bit trickier if you’re buying fresh meat, seafood, or poultry, since ingredients often aren’t listed. If that’s the case at your grocer, don’t hesitate to talk to the butcher if that’s an option. “It’s possible to think you’re eating a natural whole diet and [still] getting substantial amount of phosphates with meats, poultry, and seafood,” says Brissette. She says you can assume your meat has been enhanced, usually with phosphates, if the sodium content is more 120 mg for one 4-ounce portion. “If they’ve injected a sodium, it’s more than likely a phosphate solution,” she says.

Cording adds that instead of counting the phosphorus in your foods, it’s better for your overall health to just avoid processed foods as much as possible and focus on eating more whole, fresh foods—especially fruits and veggies. “Phosphate is usually used in foods that are not that great for you anyway, like processed meat and cheeses. In general, these foods are also high in sodium and other additives that aren’t so good for you,” she says.

Basically, phosphates are tricky ingredients that have been linked to a host of negative health effects. Consider it yet another reason to ditch overly-processed foods for good.

Now that you have the DL on phosphates, here’s what you should really know about the great GMO debate. And if you’re not sure where to start with eating whole foods, why not check out the 20 veggie challenge?